Optoelectronic devices used in fiber optic communication transmitters and/or receivers are typically required to perform in varying environmental conditions and within tight specifications and tolerances. As the accumulation of moisture may have a detrimental effect on such components, it is beneficial to provide protection of the components from moisture.
In the specific case of a photodiode array ROSA on a ceramic substrate, the ROSA typically includes a metal retainer that is directly attached to a ferrule that houses an array of fibers. As it is typically necessary to place the photodiode array a relatively short distance from the ends of the fibers to maintain sufficient optical coupling, the space within the ceramic substrate within which to mount and wirebond the photodiode array is often tight and difficult to work with.